A great portion of man-made energy is used for heating and cooling. For example, a large portion of utility bills in Summer are often associated with energy used for running air-conditioners to keep the indoor temperatures low, whereas, in Winter, energy is used for running heaters to maintain the indoors warm. Most of the energy wasted during heating and cooling may be attributed to poor insulation against heat loss. In most prior arts on heat resistant paints, an ordinary paint is turned into a heat resistant paint by being blended with particulates and voids. In other similar prior arts, colloidal particles are blended in film-forming materials, and such materials are applied over substrates such as windowpanes or glasses to block infrared electromagnetic waves.
One class of prior arts on heat blocking technologies involves heat resistant paints. In U.S. Pat. No. 4,623,390, glass microspheres or hollow glass extenders are blended in an ordinary paint to reduce direct thermal conductivity, which greatly improves insulation against heat loss. In one embodiment, glass microspheres of diameters ranging from approximately 50 microns to 150 microns are blended in an ordinary paint, whereas, in an another embodiment, glass microspheres of approximately 100 microns in diameters are blended in an ordinary paint. However, U.S. Pat. No. 4,623,390 does not discuss any aspects of multi-layered coating structures discussed in the present invention.
In U.S. Pat. No. 8,287,998, hollow microspheres selected from glass, ceramic, and organic polymer microspheres with mean particle sizes between 0.5 micron and 150 microns are blended in an ordinary paint to reduce direct thermal conductivity. Furthermore, in U.S. Pat. No. 8,287,998, infrared reflective pigment materials are also incorporated in an ordinary paint mixture to reduce thermal conductivity associated with radiative heat transfers. However, U.S. Pat. No. 8,287,998 does not discuss any aspects of the multi-layered coating structures discussed in the present invention.
U.S. Pat. No. 2010/0,203,336 discloses a solar reflective roofing granule. In one embodiment, a solar reflective granule is formed by sintering ceramic particles, wherein the sintered ceramic particles are coated with solar reflective particles. However, U.S. Pat. No. 2010/0,203,336 does not discuss any aspects of the multi-layered coating structures covered in the present disclosure.
In U.S. Pat. No. 2013/0,108,873, a roofing granule forming particle is coated with a nanoparticle layer which reflects near infrared radiation. Similarly, in U.S. Pat. No. 2013/0,161,578, a roofing granule is formed from an infrared reflecting inert mineral core particle which has naturally occurring voids (or defects). However, neither U.S. Pat. No. 2013/0,108,873 nor U.S. Pat. No. 2013/0,161,578 discuss any aspects of the multi-layered coating structures presented in the present disclosure.
U.S. Pat. No. 2008/0,035,021 discloses a method for fabricating aluminum phosphate hollow microspheres. Also, it is illustrated how such particulates may be used to improve insulation against heat loss. However, U.S. Pat. No. 2008/0,035,021 does not discuss any aspects of the multi-layered coating structures covered by the present invention.
U.S. Pat. No. 2007/0,298,242 discloses a lens for filtering optical waves, wherein the metallic nano-particulates including thin-film layers are formed on a surface of the lens. However, U.S. Pat. No. 2007/0,298,242 does not discuss any aspects of the multi-layered coating structures discussed in the present disclosure.
In U.S. Pat. No. 2007/0,036,985, indium tin oxide (ITO) particulates are blended with a film-forming mixture to form a thin-film layer which reflects infrared waves. However, U.S. Pat. No. 2007/0,036,985 does not discuss any aspects of the multi-layered coating structures illustrated in the present invention.
U.S. Pat. No. 2013/0,266,800 discloses a method for preparing aluminum-doped zinc oxide (AZO) nanocrystals. It further discloses a thin-film structure for reflecting infrared waves which uses AZO nano-particulates. However, U.S. Pat. No. 2013/0,266,800 A1 does not discuss any aspects of the multi-layered coating structures discussed in the present disclosure.
U.S. Pat. No. 7,760,424 and U.S. Pat. No. 8,009,351 disclose multi-layered thin-film structures using colloidal particles to reflect infrared electromagnetic waves. However, U.S. Pat. No. 7,760,424 and U.S. Pat. No. 8,009,351 disclose that particulates in each layer of a multi-layered structure are regularly arrayed with regular lattice spacing therebetween, whereas the present invention describes that voids are randomly distributed in each layer of a multi-layered coating system. U.S. Pat. No. 7,760,424 and U.S. Pat. No. 8,009,351 rely on the Bragg's law for the description of infrared reflections, whereas the present invention relies on the Mie scattering theory for the description of infrared reflections. In order to make visible wavelengths highly transparent, U.S. Pat. No. 7,760,424 and U.S. Pat. No. 8,009,351 require the following restrictions: a) a refractive index of particulates and a refractive index of a filler material disposed in a space between the particulates must be nearly identical, whereas in the present invention, a filler material and voids that are randomly distributed are not required to have nearly identical refractive indices. Infrared reflections in U.S. Pat. No. 7,760,424 and U.S. Pat. No. 8,009,351 strongly depend on an angle of incident incoming waves, typical characteristics of photonic crystals, and a consequence of the Bragg's law, whereas infrared reflections in the present invention do not strongly depend on an angle of incidence of incoming waves, typical characteristics of photonic crystals, and a consequence of the Bragg's law. Such noticeable differences clearly distinguish the present invention from U.S. Pat. No. 7,760,424 and U.S. Pat. No. 8,009,351.
The following prior arts on quantum dot technologies are listed here for reference: U.S. Pat. No. 8,362,684, U.S. Pat. No. 8,395,042, U.S. Pat. No. 2013/0,003,163, and U.S. Pat. No. 2013/0,207,073. Although these prior arts are technologically unrelated to the present invention, there are similarities in the distribution of voids in each layer of a multi-layered coating system. However, the present disclosure and the listed prior arts on quantum dot technologies are based on fundamentally different laws of physics and two should not be regarded as being the same.